Electric firing device for projectiles



March 30, 1965.

J. ROCHAT ELECTRIC FIRING DEVICE FOR PROJECTILES Filed Nov. 26, 1962 z i wWI 6 6 M y 4 3% m. z

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n MI 13% Mum/10mg JEAN H United States Patent 3,175,496 ELECTRIC FIRHJG DEVICE FGR PROJECTILES Jean Rochat, Mont-la-Ville, Vaud, Switzerland Filed Nov. 26, 1962, Ser. No. 247,783 Claims priority, application Switzerland, Nov. 30, 1961, 13,939/ 61 4 Claims. (Cl. 102-702) The present invention concerns an electric firing device for projectiles.

In electric firing devices for projectiles, especially for self-propelled projectiles, it is necessary to provide security measures permitting the avoidance of all ignition of the explosive charge of the projectile whilst it is not discharged in the required manner.

In projectiles for fire arms having closed tubes, for example for cannons, it is easy to provide an explosive ignition device which can only be armed after the firing stroke. In fact, the acceleration of a shell, at the moment of discharge, can reach values which are much higher than the acceleration that any shell can sustain in the course of the handling, even in the case of falling on a relatively hard ground. It is thus possible to arm the ignition device by means of an inertia mechanism which reacts as soon as the acceleration is greater than a predetermined value.

The problem is more complicated in the case of selfpropelled projectiles, as the acceleration of these is relatively small and it can easily happen, in particular when projectiles are parachuted, that they are submitted to accelerations of very short duration but of a value greater than that which it has at the time of discharge.

An object of the present invention is to avoid all danger of premature igniting of projectiles of this type.

According to the present invention a firing electric device for projectiles, especially for self-propelled projectiles, comprises an electric generator, a part of the magnetic circuit of which is displaceable under spring infiuence to produce the electric energy necessary to fire the projectile, this part of the magnetic circuit being maintained in position, before discharge, by a locking or holding device sensitive to the acceleration of the projectile, this locking device comprising an inertia mass displaceable against the action of a spring and against the action of a retarding device, characterised in that the locking device also comprises a brake preventing the unlocking when the acceleration of the projectile exceeds a predetermined acceleration.

The invention will now be described further,,by way of example, with reference to the accompanying drawings, in which: 1

FIG. 1 is a plan view of the device constructed in accordance with the invention;

FIG. 2 is an elevation after removal of the generator;

FIG. 3 is a section through a part of the locking mechanism of an electric generator before tripping;

FIG. 4 is a section similar to FIG. 3 of the locking mechanism after tripping; and

FIG. 5 is a constructional detail.

The firing device shown comprises a base plate 1 of insulating material and carrying a generator 2 and means for controlling the energization thereof to fire the projectile at selected degrees of acceleration.

The generator 2 has not been shown in detail as it is constructed in accordance with known electric motor principles comprising a rotor constituted by a permanent magnet. This rotor is disposed between two pole shoes 3 and 4 of a magnetic circuit having a winding 5. This rotor is rotatably integral with a disc '6 presenting two diametrically opposed slots 7, the disc 6 being influenced by a spring 8 hooked to a fixed member 9. The disc 3,175,496 Patented Mar. 30, 1965 6 is prevented from turning under the influence of the spring 8 by a finger 10 engaged in a slot 7. This finger 10 forms part of a lever 11 suspended from the shank of a screw type stud 12 on a supporting block 13 fixed to the plate 14 which constitutes a part of the frame for housing the means for retarding the mechanism as the projectile is in flight. The lower end of the lever 11, which for convenience may be termed the first lever, cooperates With the end of a second lever 15 pivoted at its other end on the shank of a screw type stud 16 fitted into the block 13, said stud 16 having its axis disposed at right angles to the axis of the stud 12.

The plate 14 is connected by spacer members 17, 1S and 19 to second plate 21). An axle 21 of which a part 22, of larger diameter passes through the plate 14, is mounted between these two plates and serves to support an arm 23, which carries a weight 24. The axle 21 carries, between the plates 14 and 20, a toothed segment 25 which meshes with a pinion 26 of a multiplying gear train. This train comprises a toothed wheel 27 in mesh with a pinion 28 rotatably integral with a disc 29 of conductive material the periphery of which passes in an air gap located between a bent sheet 30 and a permanent magnet 31.

The arm 23 carrying the weight 24 is maintained, in the stationary state, in the position shown in FIG. 2 by spring 32 fixed to the base plate 1 (FIG. 2). In this position, as is shown in FIG. 3, the arm 23 lies against a first abutment or keeper notch 43 of the lever 15 which also has a second abutment or keeper notch 35 as will be seen from FIG. 3.

The device shown is fixed in a projectile in such a manner that the longitudinal axis of the projectile is perpendicular to the base plate 1, the nose of the projectile being above the base plate 1, with reference to FIG. 2. In this way, the inertia forces acting on the weight 24 and on the arm 23 at the moment of discharge of the projectile, have the effect of turning the arm 23 around its axle 21 against the action of the spring 32. The spacer 17, which separates the plates 14 and 20, carries a leaf spring 34, the free end of which is near the edge of the disc 29.

The lever 15 presents a slot 35 which is visible in FIG. 3.

The fiunctioning of the described device is as follows:

At the time of the acceleration of the projectile at the moment of its discharge the inertia of the weight 24 makes the arm 23 pivot in clockwise direction, with reference to FIG. 2 and against the action of the spring 32. This pivoting movement is braked by the retarding device which is housed between the plates 20 and 14 because, as a result of the multiplying gear train, a displacement of the weight 24 effects a much greater displacement of the periphery of the disc 29, which constitutes a rotating body of the retarding device. This device opposes the movement of the arm 23 by virtue of the kinetic energy which must be accumulated in the moving members, especially in the disc 29 and, as a result of the braking effected by the Foucalt currents which are generated in the disc 29 as a result of its rotation in a magnetic field produced by the magnet 31.

If the duration of the acceleration of the projectile is suflicient, the rotation of the arm 23 carries on until it comes to position opposite the second abutment or keeper notch 35 of the lever 15, so that lever 15 can pivot to take up the position shown in FIG. 4, its end thus freeing the end of the lever 11. The lever 11 can then pivot around its screw 12 in a counterclockwise direction, with reference to FIG. 2, under the influence of a force exerted on the finger 10 by the edge of the slot 7 by the disc 6 which is influenced by the spring 8. When the lever 11 pivots,

the finger describes the arc of a circle and moves away from the upper face of the disc 6, so that this disc 6 is freed and can turn under the influence of the spring 8. The current produced by the generator 2 is used for charging a condenser (not shown) which permits, in known manner, the ignition of an explosive charge at the moment when it is desired.

To facilitate the disengagement of the locking device, the ends of the lever 11 and 15, which are in contact with each other, present an oblique part 36 forming a ramp, as is shown in detail in FIG. 5. Likewise, the torque exerted on the lever 11 by the disc 6 when it is locked tends to pivot the lever 11 in a counterclockwise direction, which applies its oblique surface 36 against that of the lever 15, the torque exerted on this lever 15 by this reaction application tends to turn the lever 15 in a counterclockwise direction with reference to FIGS. 3 and 4.

In the case where the projectile is submitted to accelerations of short duration, but of the order of magnitude of the acceleration of the projectile at the time of its discharge, the arm 23 can turn against the action of the spring 32. In any case, the duration of the acceleration being too short to permit the rotation of this arm to turn sufficiently to effect the disengagement of the locking device, the spring 32 brings back the arm into the position shown in FIG. 2 as soon as the acceleration has ceased. In the case where the projectile is to be submitted to a very great acceleration, for example five times as great as the normal acceleration of the discharge of the projectile, there could be feared that in spite of the short duration of this acceleration, the arm 23 would turn sufficiently to induce the arming of the firing device. The spring 34 nevertheless wards off this eventuality, as it is submitted to the same acceleration and is sufliciently deformed to lean against the edge of the disc 29. As a result a braking efiect is obtained which is as great as the acceleration and stronger, this braking efficaciously opposes all displacement of the arm 23 and of the weight 24.

Of course numerous modifications to the described device are possible and one advantageous variant would consist in mounting the weight 24 slidably on the arm 23 and providing means for locking this weight on the arm. Thus the distance of the weight 24 from the axle 22 can be modified which permits obtaining the adjustment of the minimum acceleration to which the projectile is subjected to permit the rotation of the arm 23 against the action of the spring 32.

I claim:

1. A firing device for projectiles, comprising,

a base and a frame,

an electric generator on said base,

retarding means for controlling said generator also on said base including, a member swingable relative to the plane of said base about an axle mounted in said frame and connected to multiplying gearing and a disc driven by said mechanism and whose periphery moves in the field of a permanent magnet,

a brake for engaging said disc when acceleration is greater than the normal acceleration at the start of the shot,

a spring for biasing said member to normal inoperative position,

and means maintaining said member poised for predetermined periods of acceleration.

2. A firing device according to claim 1, wherein the means maintaining said member poised also includes a pair of levers frictionally engaged at their free ends, one of said levers having first and second spaced keeper notches, the first notch normally receiving the arm to maintain it poised for a predetermined period of acceleration, and

(if. if the duration of the period of acceleration of the projectile exceeds the predetermined initial setting, said arm will rest in the second keeper notch.

3. A firing device for projectiles, comprising,

a base,

a frame,

an electric generator on the base,

a spring biased disc having opposite notches mounted on the generator,

means for controlling said generator including,

an arm having a weight at one end and pivotally connected at the other end to retarding mechanism including gearing connected with said arm operating a disc whose periphery is in the field of a permanent magnet,

a spring for biasing said arm to normal inoperative position,

and a pair of levers frictionally engaged at their free ends, one of said levers having an offset arm for engaging a notch in the disc and the other lever having s aced first and second keeper notches, the first notch normally receiving the arm to maintain it poised for a predetermined initial period of acceleration, and when the duration of the period of acceleration exceeds the predetermined initial setting, said arm will be further turned until it rests in the second keeper notch.

4. An electric firing device for projectiles, comprising,

an electric generator mounted on a base and including a rotor having a winding, pole pieces and a fixed memher,

a spring controlled disc mounted on said fixed member and having oppositely disposed peripheral notches,

a frame on the base,

an axle mounted for rotation in said frame,

an arm having a weight at its outer end and its inner end connected to said axle,

a spring having one end secured to the base and its free end engaging in maintaining said arm in a normally predetermined elevated position,

and means responsive to variable inertia conditions during the flight of the projectile for controlling the arm between initial and subsequent operative positions relative to the generator, said means comprising,

a multiplying gear train connected with the said axle of said arm and including a disc having its periphery portion operating in the field of a permanent magnet,

a spring mounted on said frame and having its free endengageable with said disc,

a first lever having first and second spaced keeper notches in one edge and pivotally supported on a pivot at its upper end on said frame, said arm normally resting in said first notch,

a second lever supported at its upper end on said frame by a pivot disposed at right angles to said pivot, said lever having an angularly offset portion engageable with a related notch of the disc,

and means at the lower ends of said first and second levers normally causing them to be in frictional engagement to maintain the arm in the said first notch.

References Cited by the Examiner UNITED STATES PATENTS 2,192,542 3/40 Benedetti 10270.2 2,642,801 6/53 Gleason l0270.2 2,918,007 12/59 Faugg l0270.2

SAMUEL FEINBERG, Primary Examiner.

BENJAMIN A. BORCHELT, Examiner. 

1. A FIRING DEVICE FOR PROJECTILES, COMPRISING, A A BASE AND A FRAME, AN ELECTRIC GENERATOR ON SAID BASE, RETARDING MEANS FOR CONTROLLING SAID GENERATOR ALSO ON SAID BASE INCLUDING, A MEMBER SWINGABLE RELATIVE TO THE PLANE OF SAID BASE ABOUT AN AXLE MOUNTED IN SAID FRAME AND CONNECTED TO MULTIPLYING GEARING AND A DISC DRIVEN BY SAID MECHANISM AND WHOSE PERIPHERY MOVES IN THE FIELD OF PERMANENT MAGNET, A BRAKE FOR ENGAGING SAID DISC WHEN ACCELERATION IS GREATER THAN THE NORMAL ACCELERATION AT THE START OF THE SHOT, A SPRING FOR BIASING SAID MEMBER TO NORMAL INOPERATIVE POSITION, AND MEANS MAINTAINING SAID MEMBER POISED FOR PREDETERMINED PERIODS OF ACCELERATION. 